GrassBase - The Online World Grass Flora


W.D. Clayton, M. Vorontsova, K.T. Harman & H. Williamson

© Copyright The Board of Trustees, Royal Botanic Gardens, Kew.

Thyrsostachys siamensis

HABIT Perennial; caespitose. Rhizomes short; pachymorph. Culms erect; 700–1300 cm long; 20–60 mm diam.; woody. Culm-internodes terete; with small lumen; 15–30 cm long. Lateral branches dendroid. Branch complement many; in a horizontal line; with 1 branch dominant; thinner than stem. Culm-sheaths persistent; chartaceous; pubescent; hairy throughout; with white hairs; without auricles. Culm-sheath blade triangular. Leaves cauline; 4–12 per branch. Leaf-sheath oral hairs lacking, or scanty. Ligule an eciliate membrane. Leaf-blade base with a brief petiole-like connection to sheath. Leaf-blades deciduous at the ligule; lanceolate; 7–15 cm long; 6–12 mm wide. Leaf-blade venation without cross veins. Leaf-blade surface pubescent; hairy abaxially. Leaf-blade margins scabrous.

INFLORESCENCE Synflorescence bractiferous; fasciculate; with spathaceous subtending bracts; bracts 10–20 mm long; with axillary buds at base of spikelet; with ultimate bract subtending a compact bracteolate fascicle of spikelets; prophyllate below lateral spikelets.

Fertile spikelets sessile.

FERTILE SPIKELETS Spikelets comprising 2 fertile florets; with a barren rhachilla extension. Spikelets lanceolate; laterally compressed; 17 mm long; breaking up at maturity; disarticulating below each fertile floret.

GLUMES Glumes persistent; similar; shorter than spikelet. Lower glume oblong; 0.7–0.8 length of upper glume; membranous; without keels; 9 -veined. Lower glume surface pubescent. Lower glume apex acute. Upper glume oblong; 1 length of adjacent fertile lemma; membranous; without keels; 9 -veined. Upper glume surface pubescent. Upper glume apex acute.

FLORETS Fertile lemma oblong; 12.5 mm long; membranous; without keel; 13–19 -veined. Lemma surface pubescent. Lemma apex acute. Palea 1 length of lemma; chartaceous; 7–9 -veined. Palea keels ciliate. Palea apex dentate (upper), or lobed (lower for 0.5 its length). Rhachilla extension 0.5 length of fertile floret.

FLOWER Lodicules absent. Anthers 6; 3.5 mm long. Stigmas 1. Ovary umbonate; glabrous.

FRUIT Caryopsis with adherent pericarp; 6–8 mm long.

DISTRIBUTION Asia-temperate: China. Asia-tropical: India and Indo-China.

NOTES Bambuseae. Lin.

Please cite this publication as detailed in How to Cite Version: 3rd February 2016.